Coercion is an inherently game-theoretic process: the coercer threatens punishment in the hope that a rational player will then deviate from his original plans and obey the coercer. Previous definitions simplify matters by focusing on the indistinguishability of a player that obeys the coercer, to one that deceives the coercer by simulating compliance while following his own objective, e.g., casting a vote. However, this comes at a loss of expressiveness when the goal is to quantify the amount of coercion resistance that, e.g., an electronic voting protocol provides.

We introduce a framework for a game-theoretic treatment of the problem and point out that, even in an ideal vote, the small size of a voting district does indeed make voters for fringe parties vulnerable to coercion. We present our initial definition, which we unfortunately found out to be too restrictive, and discuss potential solutions.

Robert Künnemann is a postdoc at the Information Security & Cryptography group, CISPA, at Saarland University. He was previously a postdoc at Technische Universtät Darmstadt, and completed his PhD in 2013 with INRIA research teams SECSI and PROSECCO at the École Normale Supérieure de Cachan, under the supervision of Steve Kremer and Graham Steel.